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Volcanoes are among the most destructive and surprising phenomena on the planet. But this burning rift has done more than just destroy. They also create.
In a new study, researchers in Russia report the discovery of one such creation, an unusual mineral that has never been documented by scientists: a fascinating blue-and-green crystalline substance, which the team calls. petrovite.
The mineral is found in volcanic landscapes in Russia’s Far East, above the Tolbachik Volcano on the Kamchatka Peninsula.
Blue cryptocrystalline crust of petrovite. (Filatov et al., Mineralogical Magazine, 2020)
The history of the Tolbachik eruption dates back thousands of years, but more recently, two notable events stand out: the “Great Tolbachik Gap Eruption” of 1975-1976 and a second smaller sequel that occurred between 2012-2013.
The force of the eruption during the first event ripped apart many cinder cones in the volcanic complex, opening up the rocky terrain that has since been discovered as a rich layer of unidentified fumarole and mineral deposits never seen anywhere else.
In total, the Tolbachik volcano claims that 130 types of mineral localities have been identified here for the first time, the most recent being petrovite, a sulfate mineral that forms blue globular aggregates of tabular crystals, many of which contain gas inclusions. .
The specimens studied here were found in 2000, near the second coal cone associated with the 1975 eruption, and have been preserved for further analysis. It may have been a long time ago, but that analysis now reveals that this bright blue mineral exhibits molecular features rarely seen before.
The copper atoms in the crystal structure of petrovite have an unusual and extremely rare coordination of seven oxygen atoms, ”explains Stanislav Filatov, lead researcher and crystallographer at the University of St. Petersburg.
“Such coordination is only characteristic of some compounds, as is the suggestion of cinchonaite”.
Petrovite single grains. (Filatov et al., Mineralogical Magazine, 2020)
Saranchinaite, identified several years ago by another St. Petersburg team, was also found in Tolbachik and, like petrovite, was also found conspicuously colored on its own.
In the case of petrovite, the mineral, which is thought to crystallize by direct precipitation of volcanic gas, takes the form of a blue cryptocrystalline crust enveloping a fine pyroclastic material.
On a chemical level, petrovite represents a new type of crystalline structure, although it bears some resemblance to the suggestion of chinaite, from which it can be produced, hypothetically.
Notably, petrovite’s molecular skeleton – made up of oxygen, sodium sulfur, and copper atoms – is effectively porous in nature, exhibiting interconnected pathways that allow sodium ions to migrate through the structure.
Because of this behavior – and if we can replicate the structure in the lab – the team thinks this could lead to important applications in materials science, potentially enabling new ways of developing cathodes for use in batteries and electrical devices.
Crystal structure showing the sodium migration path. (Filatov et al., Mineralogical Magazine, 2020)
“Currently, the biggest problem with these uses are the small amounts of the transition metal – copper – in the crystal structure of the mineral,” Filatov said.
“This can be solved by synthesizing a compound with the same structure as petrovite in the laboratory.”
These results are reported in Mineralogi magazine.
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